Back extension backrest

ABSTRACT

A backrest for use with a chair that has a seat and a base. The backrest includes a lower member having a proximal end and a distal end, and upper member attached to the chair at the proximal end. A spring-hinge mechanism pivotally connects the lower member in the vicinity of the distal end to the upper member. A lumbar support is attached to the upper member and the lower member and spans the spring-hinge mechanism. In use a user sitting on the seat may, by anterior flexing of the user&#39;s upper back cause the upper member to pivot relative to the lower member from an unflexed position to a flexed position.

RELATED APPLICATION

This application claims the benefit of and priority to U.S. Provisional Application Ser. No. 61/170,036, filed Apr. 15, 2009, the contents of which are incorporated by reference herein in its entirety.

BACKGROUND

1. Field

The present invention relates to backrests for chairs and more particularly to office-chair backrests intended to alleviate back problems associated with prolonged sitting in conventional office chairs.

2. General Background

Back problems and associated back pain are widespread. One-half of all working Canadians admit to having back or neck pain symptoms each year. Back pain is the second most common reason for missed work and visits to the doctors' offices. Most cases of back pain are mechanical or non-organic, meaning they are not caused by underlying medical conditions, such as inflammatory arthritis, infection, fracture or cancer. Canadians spend billions each year on neck or back pain. Experts estimate that as much as 80% of the population will experience a back problem at some time in their lives.

The ubiquity of computerized workstations has caused an epidemic of neck, mid-back, and low-back pain, and headaches. The human body was not designed to sit all day. In adults, spinal discs in your spine have no blood supply; studies show that around 12-14 years of age, the blood supply to the discs atrophies. That means there is no direct circulation going through a disc. There is blood supply outside the discs in people of all ages. This blood supply must be forced into the disc to prevent disc damage and allow healing to occur. Since there is no direct blood supply into a disc, the only way to get nutrition and oxygen into a disc and waste products out is by imbibition, which is augmented by movement of the spine.

Research has indicated that the movement adequate to force blood flow in and waste products out must be performed twice daily to maintain healthy hydrated spinal discs, ligaments and tendons. It has been found that it takes up to 500 days to force blood flow in and waste products out in those patients who are sedentary and don't or can't do the correct types of motion necessary to cause the desired exchange.

As well, sitting for extended periods in the average office chair often results in a forward-slouching posture, as such chairs tend to motivate and guide poor posture with forward head posture and a collapsed or reversed lumbar curve. This position puts strain upon the lower back.

SUMMARY

In one aspect, the invention consists of a backrest for use with a chair having a seat and a base, the backrest including: a lower member having a proximal end and a distal end, and attached to the chair at the proximal end; an upper member; a spring-hinge mechanism pivotally connecting the lower member in the vicinity of the distal end to the upper member; a lumbar support attached to the upper member and the lower member and spanning the spring-hinge mechanism wherein, in use a user sitting on the seat may, by anterior flexing of the user's upper back cause the upper member to pivot relative to the lower member from an unflexed position to a flexed position.

The backrest has three main purposes: to correct the posture of the one who is sitting; to strengthen the internal muscles associated with spinal support; and to increase circulation up and down the entire spine. This is done by means of the rearward (or anterior) flexing of the upper body while sitting. The backrest flexes, or hinges, from a point midway up the lumbar curve. The backrest foam and fabric cover are not split, but they flex in order to accommodate the motion. The hinged portions of the backrest are spring-loaded, so that they return to the neutral or starting position.

In order to use the backrest, the sitter engages his or her spine with the backrest lumbar support, and flexes backwards several times.

Possible variations involve moving the hinging point higher or lower, making the spring resistance variable, providing a height-adjustable headrest, providing an adjustable tilt for the upper portion of the backrest.

DRAWINGS

The above-mentioned features and objects of the present disclosure will become more apparent with reference to the following description taken in conjunction with the accompanying drawings wherein like reference numerals denote like elements and in which:

FIG. 1 is a side elevation view of an embodiment of the invention shown unflexed.

FIG. 2 is a perspective cut away view of the backrest shown in FIG. 1, shown unflexed.

FIG. 3 is a perspective cut away view of the backrest shown in FIG. 2, shown flexed.

FIG. 4 is a side elevation view of the backrest shown in FIG. 2, shown unflexed.

FIG. 5 is a side elevation view of the backrest shown in FIG. 4, shown flexed.

FIG. 6 is a side elevation view of a variation on the embodiment illustrated in FIG. 1 which includes an upper-back roller.

DETAILED DESCRIPTION

FIGS. 1 through 5 show a backrest 10 embodiment of the present invention as a feature of an otherwise-conventional stylized office chair 12 having a seat 14 and base 16. FIG. 6 illustrates a variation of the embodiment illustrated in FIGS. 1 through 5.

Referring to FIG. 1, the backrest 10 includes a lower member 18 and an upper member 20, attached one to the other by a spring-hinge mechanism 22. Spanning the lower member 18 and upper member 20, and projecting away from the spring-hinge mechanism 22 towards the front of the office chair 12 there is a padded lumbar support 24.

The spring-hinge mechanism 22 is configured to permit the lower member 18 and upper member 20 to pivot relative to each other between an upright, essentially aligned, unflexed position, as shown in FIGS. 1 and 2, and a flexed position, an example of which is shown in FIG. 5. The spring-hinge mechanism 22 is configured to resiliently bias the lower member 18 and upper member 20 into the unflexed position, such that a user of the office chair 12 experiences some resistance when moving from the unflexed position illustrated in FIG. 4 to the flexed position illustrated in FIG. 5 and the backrest 20 will not remain in the flexed position unless a suitable force is maintained. Preferably, the spring-hinge mechanism 22 is configured, or other features of the backrest 10 are configured, to limit the range of movement of the upper member 20 relative to the lower member 18, such that the pivot angle between the unflexed position illustrated in FIG. 4 and the normal maximum flexed position illustrated in FIG. 5 is about 30 degrees.

Referring to FIG. 4, the spring-hinge mechanism 22 may be configured, or other features of the backrest 10 may be configured to permit adjustment of the alignment of the lower member 18 and upper member 20 when in the unflexed position and to permit adjustment of the range of movement between the unflexed position and the normal maximum flexed position illustrated in FIG. 5.

The lumbar support 24 deforms to accommodate the pivoting of the lower member 18 and upper member 20 between the unflexed position illustrated in FIG. 4 and flexed position illustrated in FIG. 5. Preferably the lumbar support 14 has a suitable unsegmented surface configured to accommodate the pivoting of the lower member 18 and upper member 20, and the associated deformation of the lumbar support 24, without resorting to openings that might tend to undesirably interact with the users clothing when the backrest 10 is moved between the flexed and unflexed positions illustrated in FIGS. 4 and 5.

In order to use the backrest 10, the user engages his or her back with the lumbar support 24, and by applying a force by means of a rearward (or anterior) flexing of his or her upper body, moves the backrest 10 from the unflexed position illustrated in FIG. 4 to the flexed position illustrated in FIG. 5. Used in this way, the backrest 10 assists to correct the posture of the one who is sitting, strengthen the internal muscles associated with spinal support and to increase circulation up and down the entire spine.

The backrest 10 is intended to provide benefits by way of facilitating desired motion rather than by strength training per se, and thus the resistance to the movement between the unflexed position illustrated in FIG. 4 and the flexed position illustrated in FIG. 5 provided by the backrest 20 is preferably relatively minimal. Preferably, the resistance is adjustable.

The backrest 10 is preferably configured to permit adjustment of the location of the lumbar support 24 relative to the seat 14. The backrest 10 is preferably configured so as to permit vertical adjustment of the location of the pivot axis relative to the seat 14 and lumbar support 24. The backrest 10 is preferably attached to the seat 14 and base 16 in such a way as to permit adjustment of the tilt of the backrest 10 relative to the seat 14 and base 16.

Variations

Referring to FIG. 6, there is illustrated a variation of the backrest 10 which includes a height adjustable headrest or an upper-back roller 26 which is provided in the vicinity of the upper end of the upper member 20. In the illustrated embodiment, the upper-back roller 26 is rotatably attached to the upper member 20 so as to rotate about a generally horizontal axis. The upper-back roller 26 preferably has a padded or resiliently flexible surface 28 for user comfort. The upper-back roller 26 shown in the drawings is generally cylindrical, but other configurations may also be suitable, such as spherical, combined conical, ridged, irregular etc. Upper-back roller 26 rolls during the flexing to prevent rubbing with the spine, and to help massage the upper back muscles.

In order to use the backrest 10 with upper-back roller 26, the user engages his or her back with the lumbar support 24, and by applying a force to the upper-back roller 26 by means of a rearward (or anterior) flexing of the upper body, moves the backrest 10 between the unflexed position illustrated in FIG. 4 and flexed position illustrated in FIG. 5, preferably several times. The upper-back roller 26 rolls during such flexing, which tends to reduce frictional resistance to the flexing and to have a massaging effect along the user's upper spine. Used in this way, the backrest 10 assists to: correct the posture of the one who is sitting; to strengthen the internal muscles associated with spinal support; and to increase circulation up and down the entire spine. The upper-back roller 26 is preferably positioned so that it will be adjacent the users upper thoracic vertebrae (T1-T7) in the unflexed position and when moving between the unflexed position and the flexed position illustrated in FIGS. 4 and 5. Since this is a common area for the accumulation of sitting-related stress, the rolling action has a desirable ancillary massage effect. Some who have tried the backrest 10 have expressed a desire to have the roller extend in to the cervical area, up to and including C1. Since the amount of force required to flex the backrest 10 is minimal, it is understood that there should be no spinal problems associated with this upper limit of roller extension. The range of travel of the upper-back roller along the user's back and the resistance to the movement between the unflexed position and the flexed position illustrated in FIGS. 4 and 5 provided by the backrest 20, may be determined by user comfort.

While the apparatus and method have been described in terms of what are presently considered to be the most practical and preferred embodiments, it is to be understood that the disclosure need not be limited to the disclosed embodiments. It is intended to cover various modifications and similar arrangements included within the spirit and scope of the claims, the scope of which should be accorded the broadest interpretation so as to encompass all such modifications and similar structures. The present disclosure includes any and all embodiments of the following claims. 

1. A backrest for use with a chair having a seat and a base, the backrest comprising: a) a lower member having a proximal end and a distal end, and attached to the chair at the proximal end; b) an upper member; c) a spring-hinge mechanism pivotally connecting the lower member in the vicinity of the distal end to the upper member; and d) a lumbar support attached to the upper member and the lower member and spanning the spring-hinge mechanism wherein, in use a user sitting on the seat may, by anterior flexing of the user's upper back cause the upper member to pivot relative to the lower member from an unflexed position to a flexed position.
 2. The backrest as defined in claim 1, wherein an upper-back roller is attached to the upper member distal from the spring-hinge mechanism.
 3. A backrest for use with a chair having a seat and a base, the backrest comprising: a) a lower member having a proximal end and a distal end, and attached to the chair at the proximal end; b) an upper member; c) a spring-hinge mechanism pivotally connecting the lower member in the vicinity of the distal end to the upper member; d) a lumbar support attached to the upper member and the lower member and spanning the spring-hinge mechanism; and c) an upper-back roller attached to the upper member distal from the spring-hinge mechanism; wherein, in use a user sitting on the seat may, by anterior flexing of the user's upper back cause the upper member to pivot relative to the lower member from an unflexed position to a flexed position. 